haydenrachelbacknew.jpgAfter calling off their engagement this past August, Rachel Bilson and Hayden Christensen are back together.

A source tells People that the duo are dating again, and Christensen was seen leaving Bilson's house in Los Feliz last week, which made us wonder.

There have been all sorts of rumors about these two, but we're hearing the main reason behind their split was the distance between the two -- Rachel lives in LA while Hayden resides in Canada.

Christensen and Bilson met on the set of Jumper in 2007, and got engaged in December 2008.